1. Field of the Invention
The present invention relates to an image forming apparatus wherein a user can suitably change reference adjustment data of exposure reference, toner density reference, etc. by operating a combination of various keys provided originally on an operation panel.
2. Description of the Related Art
In general, an image forming apparatus represented by an electronic copying apparatus has an auto exposure adjustment function and a manual exposure adjustment function. This type of electronic copying apparatus is disclosed, for example, in U.S. Pat. No. 4,627,713. In addition, there has been proposed an electronic copying apparatus having a function of detecting the density of toner in a developing device and controlling addition of toner. An example of this electronic copying apparatus is disclosed in Japanese Patent Application No. 300712/89 filed Nov. 21, 1989 by the same applicant as the present application.
In the case of new copying apparatuses or copying apparatuses just after periodic maintenance service, satisfactory copies are normally obtained by auto exposure or standard set values of manual exposure (default values; manual center). However, after a number of copies have been made, the brightness (density) of a copied image varies due to a variation in characteristics of a developer, deterioration of characteristics of a photosensitive drum, etc., even if an exposure lamp is stably driven by the same voltage.
When satisfactory copies are not obtained by auto exposure or standard set values of manual exposure, each user must adjust the exposure amount in the manual exposure adjustment mode before taking a copy, though this is troublesome. However, several copies must be produced on trial until the user can understand the degree by which the exposure amount should be corrected. Thus, erroneous copies are produced, at the beginning, due to auto exposure or standard set values of manual exposure.